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Subject[PATCH 28/35] Unionfs: Miscellaneous helper functions
Date
From: Josef "Jeff" Sipek <jsipek@cs.sunysb.edu>

This patch contains miscellaneous helper functions used thoughout Unionfs.

Signed-off-by: Josef "Jeff" Sipek <jsipek@cs.sunysb.edu>
Signed-off-by: David Quigley <dquigley@fsl.cs.sunysb.edu>
Signed-off-by: Erez Zadok <ezk@cs.sunysb.edu>
---
fs/unionfs/subr.c | 170 +++++++++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 170 insertions(+), 0 deletions(-)
diff --git a/fs/unionfs/subr.c b/fs/unionfs/subr.c
new file mode 100644
index 0000000..f002f19
--- /dev/null
+++ b/fs/unionfs/subr.c
@@ -0,0 +1,170 @@
+/*
+ * Copyright (c) 2003-2006 Erez Zadok
+ * Copyright (c) 2003-2006 Charles P. Wright
+ * Copyright (c) 2005-2006 Josef 'Jeff' Sipek
+ * Copyright (c) 2005-2006 Junjiro Okajima
+ * Copyright (c) 2005 Arun M. Krishnakumar
+ * Copyright (c) 2004-2006 David P. Quigley
+ * Copyright (c) 2003-2004 Mohammad Nayyer Zubair
+ * Copyright (c) 2003 Puja Gupta
+ * Copyright (c) 2003 Harikesavan Krishnan
+ * Copyright (c) 2003-2006 Stony Brook University
+ * Copyright (c) 2003-2006 The Research Foundation of State University of New York
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include "union.h"
+
+/* Pass an unionfs dentry and an index. It will try to create a whiteout
+ * for the filename in dentry, and will try in branch 'index'. On error,
+ * it will proceed to a branch to the left.
+ */
+int create_whiteout(struct dentry *dentry, int start)
+{
+ int bstart, bend, bindex;
+ struct dentry *hidden_dir_dentry;
+ struct dentry *hidden_dentry;
+ struct dentry *hidden_wh_dentry;
+ char *name = NULL;
+ int err = -EINVAL;
+
+ verify_locked(dentry);
+
+ bstart = dbstart(dentry);
+ bend = dbend(dentry);
+
+ /* create dentry's whiteout equivalent */
+ name = alloc_whname(dentry->d_name.name, dentry->d_name.len);
+ if (IS_ERR(name)) {
+ err = PTR_ERR(name);
+ goto out;
+ }
+
+ for (bindex = start; bindex >= 0; bindex--) {
+ hidden_dentry = unionfs_lower_dentry_idx(dentry, bindex);
+
+ if (!hidden_dentry) {
+ /* if hidden dentry is not present, create the entire
+ * hidden dentry directory structure and go ahead.
+ * Since we want to just create whiteout, we only want
+ * the parent dentry, and hence get rid of this dentry.
+ */
+ hidden_dentry = create_parents(dentry->d_inode,
+ dentry, bindex);
+ if (!hidden_dentry || IS_ERR(hidden_dentry)) {
+ printk(KERN_DEBUG "create_parents failed for "
+ "bindex = %d\n", bindex);
+ continue;
+ }
+ }
+
+ hidden_wh_dentry = lookup_one_len(name, hidden_dentry->d_parent,
+ dentry->d_name.len + UNIONFS_WHLEN);
+ if (IS_ERR(hidden_wh_dentry))
+ continue;
+
+ /* The whiteout already exists. This used to be impossible, but
+ * now is possible because of opaqueness. */
+ if (hidden_wh_dentry->d_inode) {
+ dput(hidden_wh_dentry);
+ err = 0;
+ goto out;
+ }
+
+ hidden_dir_dentry = lock_parent(hidden_wh_dentry);
+ if (!(err = is_robranch_super(dentry->d_sb, bindex))) {
+ err = vfs_create(hidden_dir_dentry->d_inode,
+ hidden_wh_dentry,
+ ~current->fs->umask & S_IRWXUGO, NULL);
+
+ }
+ unlock_dir(hidden_dir_dentry);
+ dput(hidden_wh_dentry);
+
+ if (!err || !IS_COPYUP_ERR(err))
+ break;
+ }
+
+ /* set dbopaque so that lookup will not proceed after this branch */
+ if (!err)
+ set_dbopaque(dentry, bindex);
+
+out:
+ kfree(name);
+ return err;
+}
+
+/* This is a helper function for rename, which ends up with hosed over dentries
+ * when it needs to revert. */
+int unionfs_refresh_hidden_dentry(struct dentry *dentry, int bindex)
+{
+ struct dentry *hidden_dentry;
+ struct dentry *hidden_parent;
+ int err = 0;
+
+ verify_locked(dentry);
+
+ lock_dentry(dentry->d_parent);
+ hidden_parent = unionfs_lower_dentry_idx(dentry->d_parent, bindex);
+ unlock_dentry(dentry->d_parent);
+
+ BUG_ON(!S_ISDIR(hidden_parent->d_inode->i_mode));
+
+ hidden_dentry = lookup_one_len(dentry->d_name.name, hidden_parent,
+ dentry->d_name.len);
+ if (IS_ERR(hidden_dentry)) {
+ err = PTR_ERR(hidden_dentry);
+ goto out;
+ }
+
+ dput(unionfs_lower_dentry_idx(dentry, bindex));
+ iput(unionfs_lower_inode_idx(dentry->d_inode, bindex));
+ unionfs_set_lower_inode_idx(dentry->d_inode, bindex, NULL);
+
+ if (!hidden_dentry->d_inode) {
+ dput(hidden_dentry);
+ unionfs_set_lower_dentry_idx(dentry, bindex, NULL);
+ } else {
+ unionfs_set_lower_dentry_idx(dentry, bindex, hidden_dentry);
+ unionfs_set_lower_inode_idx(dentry->d_inode, bindex,
+ igrab(hidden_dentry->d_inode));
+ }
+
+out:
+ return err;
+}
+
+int make_dir_opaque(struct dentry *dentry, int bindex)
+{
+ int err = 0;
+ struct dentry *hidden_dentry, *diropq;
+ struct inode *hidden_dir;
+
+ hidden_dentry = unionfs_lower_dentry_idx(dentry, bindex);
+ hidden_dir = hidden_dentry->d_inode;
+ BUG_ON(!S_ISDIR(dentry->d_inode->i_mode) ||
+ !S_ISDIR(hidden_dir->i_mode));
+
+ mutex_lock(&hidden_dir->i_mutex);
+ diropq = lookup_one_len(UNIONFS_DIR_OPAQUE, hidden_dentry,
+ sizeof(UNIONFS_DIR_OPAQUE) - 1);
+ if (IS_ERR(diropq)) {
+ err = PTR_ERR(diropq);
+ goto out;
+ }
+
+ if (!diropq->d_inode)
+ err = vfs_create(hidden_dir, diropq, S_IRUGO, NULL);
+ if (!err)
+ set_dbopaque(dentry, bindex);
+
+ dput(diropq);
+
+out:
+ mutex_unlock(&hidden_dir->i_mutex);
+ return err;
+}
+
--
1.4.3.3
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